A study of divalent metal cations Cu²⁺, Zn²⁺ and Pb²⁺ attachment to 3-hydroxyflavone, 5-hydroxyflavone and 5-methoxyflavone by nanoelectrospray ionization LTQ Orbitrap mass spectrometry

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• 作者：Chowdhury Hasan Sarowar^a ; ^c ; Grainne Moran^b ; ^{G.Moran@unsw.edu.au} ; Gary David Willett^a
• 关键词：Divalent metal cation ; Collision-induced dissociation ; Flavonoid ; LTQ Orbitrap mass spectrometry ; Nanoelectrospray ionization
• 刊名：International Journal of Mass Spectrometry
• 出版年：2013
• 出版时间：1 January, 2013
• 年：2013
• 卷：333
• 期：Complete
• 页码：44-54
• 全文大小：699 K

文摘

Cu²⁺, Zn²⁺ and Pb²⁺ cationized 3-hydroxyflavone, 5-hydroxyflavone and 5-methoxyflavone complexes were studied by nanoelectrospray ionization (nano-ESI) LTQ Orbitrap tandem mass spectrometry. With some exceptions, the most common types of ions observed in the nano-ESI mass spectra of Cu²⁺, Zn²⁺ and Pb²⁺ cationized 5-methoxyflavone are doubly and singly charged species [3L+M]²⁺, [2L+M]²⁺, [2L+M+NO₃]⁺, [L+M+NO₃]⁺ and [L?CH₃+M]⁺ (where L = 5-methoxyflavone and M = Cu²⁺, Zn²⁺ and Pb²⁺). Nano-ESI spectra also show [L]⁺ and [L?H]⁺ types ions for Cu²⁺ and Pb²⁺ complexes. The losses of H₂O, CHO and (CO + H₂) are predominantly observed in the nano-ESI mass spectra of Cu²⁺ cationized 5-methoxyflavone complexes. Cu²⁺ is also unique in producing a variety of reduced Cu⁺ species. The common ions observed in the nano-ESI mass spectra of 3-Hydroxyflavone and 5-hydroxyflavone with divalent cations are [3L?3H+2M]⁺, [2L?H+M]⁺ and [L?H+M]⁺ where L = 3-hydroxyflavone or 5-hydroxyflavone. Some exceptions are also observed. For example [2L?3H+2Zn]⁺ is displayed by 3-hydroxyflavone but [2L?2H+2Cu]⁺ by 3-hydroxyflavone and 5-hydroxyflavone. The losses of CHO and (CHO + CO) are observed by Cu²⁺ and Zn²⁺ but not by Pb²⁺. Tandem mass spectra on [3L+M]²⁺, [2L+M]²⁺, [2L+M+NO₃]⁺, [L+M+NO₃]⁺ complexes for 5-methoxyflavone indicate that electronic configuration of the metal cations and counter ion NO₃^? has significant influence in the observed dissociation patterns. For example, CID of [2L+Cu]²⁺ and [2L+Pb]²⁺ for 5-methoxyflavone shows unique ions [L]⁺, [L?H]⁺, [L?H₂O]⁺, [L?CHO]⁺ and [L?2H?CO₂]⁺ that were not observed by Zn²⁺ complexes. Similarly the molecular ion [L]⁺ is displayed by the [L+NO₃+Zn]⁺ complexes but not by [L+NO₃+Cu]⁺ and [L+NO₃+Pb]⁺. 3-Hydroxyflavone and 5-hydroxyflavone also show some interesting results. For example product ions that contain metal cations due to loss of CHO and CO are exclusively observed for the [L?H+Cu]⁺ complexes of 3-hydroxyflavone whereas reverse is observed for the [2L?H+Zn]⁺ complexes.